The Scrabulous application, developed by brothers Jayant and Rajat Agarwalla of Calcutta, reportedly draws more than half a million Facebook users daily. CBS's "60 Minutes" Sunday night showed Facebook founder Mark Zuckerberg playing the game. He said he plays with his grandparents.

There currently is no official online Scrabble, but Hasbro recently licensed the rights to create digital versions of its games to Electronic Arts.

Scrabulous and Facebook declined to comment, while Hasbro did not respond to requests for comment.

Some lawyers say that Hasbro appears to have a valid trademark infringement claim against the Scrabulous developers because that word is close enough to Scrabble to confuse people. "There's a psychic harm to consumers, because they're being lied to and misled into thinking there's some link here," said Jessie Beeber of Frankfurt Kurnit Klein & Selz.

A copyright claim might be harder to prove because it's not clear that board games like Scrabble can be copyrighted, said Eric Goldman, director of the High Tech Law Institute at Santa Clara University School of Law. But, he added, some judges might be inclined to stretch the law in this situation. "Courts tend to be sympathetic if it seems like gamemakers are being abused," he said.

But even if the Scrabulous developers have violated a copyright or trademark claim, the application won't necessarily disappear from Facebook soon. For one thing, it's not certain that Facebook would be liable for contributing to copyright or trademark infringement in this situation, Goldman said. In addition, proving a case or enforcing a judgment against the Agarwalla brothers who reside in India could be difficult, given the differences in intellectual property law between that country and the United States.

Still, for Facebook--which opened its site to third-party developers in June--this skirmish with Hasbro could be just the beginning of legal woes if other applications on the site arguably infringe on companies' intellectual property rights.

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